I've tried it on 100, 75, 50, 25, 0, etc.
It seemed like I lost control of my player on the higher settings. It was like I was being pulled to whoever the ball handler was even if he wasn't the man I was guarding. That's why I left it at 0. And for certain dribble spammers and speed booster it doesn't matter what setting you have it on. They will bust dribble moves that create so much space and the Stop and Go and Quick First Step and Hyper Drive badges will get you murdered on defense. Oh and the Triple Threat Juke.
The defense can't counteract some of the ways these things create space. Have you ever seen a spammer do a size-up and then go right or left and it seems like their little arm gets long as hell and the ball seems to be on a string?
Those are the worst. The ball seems to push further away from their body as they boost in the direction they are going. You can tell the way the arm looks long and deformed. You'll notice it but it happens quick.